In a typical air laid papermaking process a dried mat of fibers is broken up to free the individual fibers which are then carried by air flow to a distributor and applied to a moving forming wire. A suction box beneath the distributor pulls the fibers down onto the wire to aid in the forming of the web. After the web is laid, it is typically compressed somewhat and then strengthened by the addition of liquid binders which, when cured, hold the fibers of the web together. Such air laying processes and numerous variations thereof are well known in the art.
It is also well known that when the mat of fibers is pulverized many fibers are formed which are smaller than the openings in the forming wire or fabric and thus pass through the wire. The fine particles are carried from the suction box along with the suction air to the main suction fan and are then delivered under pressure to an air cleaner or separator. A standard type of separator uses several fiber collection units having cloth tubes descending downwardly from an intake plenum into which the fiber bearing air is discharged. The air passes through the walls of the cloth tubes and is discharged to the outside while the fines are collected on the surfaces of the tubes. Such a collection apparatus is customarily referred to in the trade as a baghouse and further includes chutes or hoppers which are mounted under each of the separator units. These chutes are ordinarily closed at their bottoms with a damper but are periodically opened to discharge the contents of the separator tubes into a collection receptacle such as a plastic bag. In large baghouses containing a number of separator units, each having a plurality of cloth tubes, the individual units are discharged one at a time by cutting off the air flow to the unit being discharged and shaking the tubes of the unit to cause the fibers to drop away from the surfaces of the tubes into the hoppers.
The fines collected from the separator have been treated as refuse and packaged for dumping in land fills or burned. A significant economic loss results, since 6% to 7% of the air layed fiber stock commonly consists of fines, and disposal of the collected fines requires significant human labor to package the fines and transport it to waste disposal sites. The handling of the discarded fines also inevitably results in an increase in the level of fines discharged to the atmosphere in the area surrounding the fiber separator, presenting a potential health hazard to workers.